1. Field of the Invention
This invention relates in general to optical switching for information and data transmission systems using light signals, such as optical fiber systems.
2. Description of the Related Art
Conventional optical fiber systems transmit information and data by laser beams through optical fibers that are bundled together. These optical fiber systems have been developed to the extent that they can efficiently and with high capacity transmit various forms of information such as voice, television and data packets.
The bandwidth of signals being transmitted through conventional fiber optic systems is growing due to increasing consumer and business demand and technological developments. The optical fibers are capable of transmitting large volumes of information over long distances, and optical fiber cables can contain large numbers of individual fibers, with as many as a thousand fibers in a single cable. These systems require methods for switching the light channels so that individual light signals are properly routed through the information networks. Switching is required where a given channel may become overloaded, where components may become damaged, or where sub-systems may require replacement.
One conventional method of switching optical channels is to convert each optical signal to an electronic signal. The electronic signal is then redirected along a different path and reconverted to an optical signal which is inserted back into an optical fiber. However, this switching method is relatively expensive and has limitations in speed and bandwidth. Another drawback is that these expensive systems require frequent replacement. Digital Wavelength Multiplexing (DWM) technology has been developed by which several wavelengths of light can be transmitted in a single fiber. Where DWM has been installed, single-frequency electronic circuits must be replaced with more expensive electronics capable of handling the multiple frequencies. This new DWM technology means that a user""s existing equipment must be upgraded to the new technology, which is very expensive.
It would be desirable to provide an optical switching system and method which would enable the switching of a large number of channels in an optical information network without the requirement of optical-to-electronic conversion and which would also not require system upgrades for handling the multiple frequencies of DWM transmissions.
It is a general object of the present invention to provide new and improved devices and methods for the switching of optical light signals. A further object is to provide methods of making optical switching devices which preserve optical alignment throughout the life of the devices. A further object is to provide devices and methods for the optical switching of light signals by the movement of mirrors. A further object is to provide optical light switching devices of the type described which can be fabricated sufficiently small to be a part of a micro-electrical mechanical system (MEMS).
The foregoing and additional objects and features of the invention will appear from the following description of the invention taken in conjunction with the accompanying drawings.